linux-kernel - [RFC][PATCH v0.3 4/6] PM: EM: Move CPU capacity check to em_adjust_new

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Message-ID: <2667366.Lt9SDvczpP@rjwysocki.net>
Date: Fri, 07 Mar 2025 20:17:19 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>,
 Peter Zijlstra <peterz@...radead.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Morten Rasmussen <morten.rasmussen@....com>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
 Pierre Gondois <pierre.gondois@....com>,
 Christian Loehle <christian.loehle@....com>,
 Viresh Kumar <viresh.kumar@...aro.org>
Subject:
 [RFC][PATCH v0.3 4/6] PM: EM: Move CPU capacity check to
 em_adjust_new_capacity()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Move the check of the CPU capacity currently stored in the energy model
against the arch_scale_cpu_capacity() value to em_adjust_new_capacity()
so it will be done regardless of where the latter is called from.

This will be useful when a new em_adjust_new_capacity() caller is added
subsequently.

While at it, move the pd local variable declaration in
em_check_capacity_update() into the loop in which it is used.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 kernel/power/energy_model.c |   40 +++++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 23 deletions(-)

--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -721,10 +721,24 @@
  * Adjustment of CPU performance values after boot, when all CPUs capacites
  * are correctly calculated.
  */
-static void em_adjust_new_capacity(struct device *dev,
+static void em_adjust_new_capacity(unsigned int cpu, struct device *dev,
 				   struct em_perf_domain *pd)
 {
+	unsigned long cpu_capacity = arch_scale_cpu_capacity(cpu);
 	struct em_perf_table *em_table;
+	struct em_perf_state *table;
+	unsigned long em_max_perf;
+
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
+	em_max_perf = table[pd->nr_perf_states - 1].performance;
+	rcu_read_unlock();
+
+	if (em_max_perf == cpu_capacity)
+		return;
+
+	pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n", cpu,
+		 cpu_capacity, em_max_perf);

 	em_table = em_table_dup(pd);
 	if (!em_table) {
@@ -740,9 +754,6 @@
 static void em_check_capacity_update(void)
 {
 	cpumask_var_t cpu_done_mask;
-	struct em_perf_state *table;
-	struct em_perf_domain *pd;
-	unsigned long cpu_capacity;
 	int cpu;

 	if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) {
@@ -753,7 +764,7 @@
 	/* Check if CPUs capacity has changed than update EM */
 	for_each_possible_cpu(cpu) {
 		struct cpufreq_policy *policy;
-		unsigned long em_max_perf;
+		struct em_perf_domain *pd;
 		struct device *dev;

 		if (cpumask_test_cpu(cpu, cpu_done_mask))
@@ -776,24 +787,7 @@
 		cpumask_or(cpu_done_mask, cpu_done_mask,
 			   em_span_cpus(pd));

-		cpu_capacity = arch_scale_cpu_capacity(cpu);
-
-		rcu_read_lock();
-		table = em_perf_state_from_pd(pd);
-		em_max_perf = table[pd->nr_perf_states - 1].performance;
-		rcu_read_unlock();
-
-		/*
-		 * Check if the CPU capacity has been adjusted during boot
-		 * and trigger the update for new performance values.
-		 */
-		if (em_max_perf == cpu_capacity)
-			continue;
-
-		pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n",
-			 cpu, cpu_capacity, em_max_perf);
-
-		em_adjust_new_capacity(dev, pd);
+		em_adjust_new_capacity(cpu, dev, pd);
 	}

 	free_cpumask_var(cpu_done_mask);